Copolymers of vinyl alcohol (VOH) with a minor amount of 2-acrylamido-2-methyl propane sulfonic acid in free acid form or as a salt of the free acid (AMPS) are known in the art and are useful for various applications, e.g., the production of cold water soluble films which can be formed into containers for predetermined batches of soaps and detergents, temporary sizing for new garments prior to their first washing and oil drilling applications where these copolymers can serve for the temporary shoring up of concrete supports used to maintain the integrity of wells prior to the setting of the concrete.
A problem with the production of these copolymers by prior art methods is that it is difficult to produce the copolymer with a sufficiently high content of polymerized AMPS while maintaining satisfactory levels of productivity and avoiding compositional drift, i.e., unacceptable variations in the content of AMPS in the copolymer from one batch to the next. Thus, any process which is capable of producing VOH/AMPS copolymers with satisfactory loading of polymerized AMPS, combined with relatively high productivity and low compositional drift, is much to be desired.